问题描述

es7.4.1客户端查询时报异常：

Caused by: java.io.IOException: Connection reset by peer
at org.elasticsearch.client.RestClient.extractAndWrapCause(RestClient.java:793)
at org.elasticsearch.client.RestClient.performRequest(RestClient.java:218)
at org.elasticsearch.client.RestClient.performRequest(RestClient.java:205)
at org.elasticsearch.client.RestHighLevelClient.internalPerformRequest(RestHighLevelClient.java:1454)
at org.elasticsearch.client.RestHighLevelClient.performRequest(RestHighLevelClient.java:1424)
at org.elasticsearch.client.RestHighLevelClient.performRequestAndParseEntity(RestHighLevelClient.java:1394)
at org.elasticsearch.client.RestHighLevelClient.search(RestHighLevelClient.java:930)
...
Caused by: java.io.IOException: Connection reset by peer
at sun.nio.ch.FileDispatcherImpl.read0(Native Method)
at sun.nio.ch.SocketDispatcher.read(SocketDispatcher.java:39)
at sun.nio.ch.IOUtil.readIntoNativeBuffer(IOUtil.java:223)
at sun.nio.ch.IOUtil.read(IOUtil.java:197)
at sun.nio.ch.SocketChannelImpl.read(SocketChannelImpl.java:380)
at org.apache.http.impl.nio.reactor.SessionInputBufferImpl.fill(SessionInputBufferImpl.java:231)
...

原因排查

es7.4.1客户端（RestHighLevelClient）使用的apache httpclient 版本为4.1.3，keepAlive默认为-1（即无限）。在某些特殊情况下，ES服务端的keepAlive短于ES客户端的keepAlive，进而导致：ES服务端已经关闭了连接，但是客户端还继续复用该连接，从而抛出上述异常。

解决方法

1. 手动设置RestHighLevelClient的keepAlive，通过KeepAliveStrategy手动配置keepAlive代码如下：

public static RestHighLevelClient createRestHighLevelClient(String esUrl, Long keepAlive) {
    
    RestClientBuilder clientBuilder = RestClient.builder(createHttpHost(URI.create(esUrl)))
            .setHttpClientConfigCallback(requestConfig -> requestConfig.setKeepAliveStrategy(
                    (response, context) -> keepAlive));
    return new RestHighLevelClient(clientBuilder);
}

    private static HttpHost createHttpHost(URI uri) {
    
        if (StringUtils.isEmpty(uri.getUserInfo())) {
    
            return HttpHost.create(uri.toString());
        }
        try {
    
            return HttpHost.create(new URI(uri.getScheme(), null, uri.getHost(), uri.getPort(), uri.getPath(),
                    uri.getQuery(), uri.getFragment()).toString());
        } catch (URISyntaxException ex) {
    
            throw new IllegalStateException(ex);
        }
    }

源码可参考

原理

1. RestHighLevelClient设置http配置的源码：

   public RestClientBuilder setHttpClientConfigCallback(HttpClientConfigCallback httpClientConfigCallback) {
         
       Objects.requireNonNull(httpClientConfigCallback, "httpClientConfigCallback must not be null");
       this.httpClientConfigCallback = httpClientConfigCallback;
       return this;
   }
   
   public interface HttpClientConfigCallback {
         
           HttpAsyncClientBuilder customizeHttpClient(HttpAsyncClientBuilder httpClientBuilder);
       }
   

2. 根据HttpAsyncClientBuilder中的部分源码可知，RestHighLevelClient默认keepAliveStrategy为DefaultConnectionKeepAliveStrategy：

   ConnectionKeepAliveStrategy keepAliveStrategy = this.keepAliveStrategy;
   if (keepAliveStrategy == null) {
         
       keepAliveStrategy = DefaultConnectionKeepAliveStrategy.INSTANCE;
   }
   

3. DefaultConnectionKeepAliveStrategy源码，如果没有在http表头中设置，默认返回-1：

   @Contract(threading = ThreadingBehavior.IMMUTABLE)
   public class DefaultConnectionKeepAliveStrategy implements ConnectionKeepAliveStrategy {
         
   
       public static final DefaultConnectionKeepAliveStrategy INSTANCE = new DefaultConnectionKeepAliveStrategy();
   
       @Override
       public long getKeepAliveDuration(final HttpResponse response, final HttpContext context) {
         
           Args.notNull(response, "HTTP response");
           final HeaderElementIterator it = new BasicHeaderElementIterator(
                   response.headerIterator(HTTP.CONN_KEEP_ALIVE));
           while (it.hasNext()) {
         
               final HeaderElement he = it.nextElement();
               final String param = he.getName();
               final String value = he.getValue();
               if (value != null && param.equalsIgnoreCase("timeout")) {
         
                   try {
         
                       return Long.parseLong(value) * 1000;
                   } catch(final NumberFormatException ignore) {
         
                   }
               }
           }
           return -1;
       }
   
   }
   

参考文档：

https://juejin.im/post/6844904069442568205

https://stackoverflow.com/questions/52997697/how-to-get-around-connection-reset-by-peer-when-using-elasticsearchs-restclie